Add optimization for CHROMIUM_subscribe_uniform extension.

content/browser/renderer_host/render_process_host_impl.cc

Index: content/browser/renderer_host/render_process_host_impl.cc
diff --git a/content/browser/renderer_host/render_process_host_impl.cc b/content/browser/renderer_host/render_process_host_impl.cc
index a32b4d79b9cfc74de5b412a83ea4f11a682e15ba..317bc3950886c7850cf90cc7eabef10c44137305 100644
--- a/content/browser/renderer_host/render_process_host_impl.cc
+++ b/content/browser/renderer_host/render_process_host_impl.cc
@@ -457,6 +457,8 @@ RenderProcessHostImpl::RenderProcessHostImpl(
       power_monitor_broadcaster_(this),
       worker_ref_count_(0),
       permission_service_context_(new PermissionServiceContext(this)),
+      pending_valuebuffer_state_(new gpu::ValueStateMap()),
+      subscribe_uniform_enabled_(false),
       weak_factory_(this) {
   widget_helper_ = new RenderWidgetHelper();
 
@@ -475,6 +477,9 @@ RenderProcessHostImpl::RenderProcessHostImpl(
                             base::Bind(&CacheShaderInfo, GetID(),
                                        storage_partition_impl_->GetPath()));
   }
+  subscribe_uniform_enabled_ =
+      base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kEnableSubscribeUniformExtension);
 
   // Note: When we create the RenderProcessHostImpl, it's technically
   //       backgrounded, because it has no visible listeners.  But the process
@@ -928,6 +933,38 @@ const base::TimeTicks& RenderProcessHostImpl::GetInitTimeForNavigationMetrics()
   return init_time_;
 }
 
+bool RenderProcessHostImpl::SubscribeUniformEnabled() const {
+  return subscribe_uniform_enabled_;
+}
+
+void RenderProcessHostImpl::OnAddSubscription(unsigned int target) {
+  DCHECK(subscribe_uniform_enabled_);
+  subscription_set_.insert(target);
+  const gpu::ValueState* state = pending_valuebuffer_state_->GetState(target);
+  if (state) {
+    SendUpdateValueState(target, *state);
+  }
+}
+
+void RenderProcessHostImpl::OnRemoveSubscription(unsigned int target) {
+  DCHECK(subscribe_uniform_enabled_);
+  subscription_set_.erase(target);
+}
+
+void RenderProcessHostImpl::SendUpdateValueState(unsigned int target,
+                                                 const gpu::ValueState& state) {
+  DCHECK(subscribe_uniform_enabled_);
+  if (subscription_set_.find(target) != subscription_set_.end()) {
+    GpuProcessHost::SendOnIO(
+        GpuProcessHost::GPU_PROCESS_KIND_SANDBOXED,
+        CAUSE_FOR_GPU_LAUNCH_NO_LAUNCH,
+        new GpuMsg_UpdateValueState(id_, target, state));
+  } else {
+    // Store the ValueState locally in case a Valuebuffer subscribes to it later
+    pending_valuebuffer_state_->UpdateState(target, state);
+  }
+}
+
 void RenderProcessHostImpl::AddRoute(
     int32 routing_id,
     IPC::Listener* listener) {